Inhibiting radiolysis of BTP molecules by addition of nitrobenzene

Autoradiolysis of extraction systems sometimes occurs during reprocessing of spent fuel, which may result in a change in the extraction behaviour of the system. In the work reported here, an aromatic heterocyclic nitrogen bearing tridentate extraction agent, 2,6-di(5,6-diethyl-1,2,4-triazin-3-yl)pyridine (a BTP), was irradiated using a 60Co source. The investigation focused on the effect of changing the organic diluent in the extraction system in order to protect the extracting agent from degradation. A relationship between the distribution ratio and extracting agent concentration was determined, and it was found that the extraction efficiency decreased with increasing irradiation dose. The effect on extraction of the degradation products from the organic diluents was also considered. (orig.)